An OLED display is a thin-film luminescent device made from organic luminescent materials and driven by a direct voltage. The OLED display technology differs from the LCD display method in that no backlight is needed and the current is used to drive an organic luminescent material film to emit light. Compared to the LCD display, the OLED display can be made lighter and thinner, have a wider viewing angle, and can significantly save electric energy. In the current OLED display, thin-film transistors (TFTs) for controlling pixels may not be uniform or stable, so that the elements in the OLED device may have brightness difference, and the display can be affected.